Scawt Hill is a

volcanic plug A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if rising volatile-charged ma ...

County Antrim County Antrim (named after the town of Antrim, ) is one of six counties of Northern Ireland and one of the thirty-two counties of Ireland. Adjoined to the north-east shore of Lough Neagh, the county covers an area of and has a population o ...

Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label= Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Nort ...

, in the

borough A borough is an administrative division in various English-speaking countries. In principle, the term ''borough'' designates a self-governing walled town, although in practice, official use of the term varies widely. History In the Middle A ...

Larne Larne (, , the name of a Gaelic territory) is a town on the east coast of County Antrim, Northern Ireland, with a population of 18,755 at the 2011 Census. It is a major passenger and freight roll-on roll-off port. Larne is administered by Mid ...

, 5 km from the village of

Ballygally Ballygally or Ballygalley (, IPA: �bˠalʲəˈɟɛhlʲiː is a village and holiday resort in County Antrim, Northern Ireland which lies on the Antrim coast, approximately north of Larne. It is also a townland of and is situated in the civil ...

.Habitas, Scawt Hill, Site Description
/ref> It gets its name from the Ulster Scots "" meaning scaly, scabby or rugged.Mountain Views, Walk Sallagh Braes to Glenarm
/ref> Alternatively, '' 'scawt' '' meaning scruffy and contemptible, and when applied to rocks, covered in barnacles.Dictionary of the Scots Language
/ref>

Discovery of minerals

Scawt Hill is notable for being the type locality for several

hydrated Drinking is the act of ingesting water or other liquids into the body through the mouth, proboscis, or elsewhere. Humans drink by swallowing, completed by peristalsis in the esophagus. The physiological processes of drinking vary widely among o ...

calcium silicates,Mineral and Locality Database, Scawt Hill
/ref> that is, the place where they were first identified. These

minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed ...

were formed when the existing

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...

of the area was intensely altered by the intrusion of the feeder tube of an ancient

volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

, now long since cooled and

eroded Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is disti ...

to its roots.Wilson, H E et al (1986) Geological Survey of Northern Ireland, HMSO Minerals that were first discovered at Scawt Hill: *

Larnite Larnite is a calcium silicate mineral with formula: Ca2SiO4. It is the calcium member of the olivine group of minerals. It was first described from an occurrence at Scawt Hill, Larne, Northern Ireland in 1929 by Cecil Edgar Tilley and named ...

(''calcium orthosilicate'') a natural form of

belite Belite is an industrial mineral important in Portland cement manufacture. Its main constituent is dicalcium silicate, Ca2SiO4, sometimes formulated as 2 CaO · SiO2 (C2S in cement chemist notation). Etymology The name was given by Törnebohm in ...

discovered in 1929Mineral and Locality Database, Larnite
/ref> and named after Larne, the nearest town * Scawtite in 1929 *

Portlandite Portlandite is a hydroxide-bearing mineral typically included in the oxide mineral class. It is the naturally occurring form of calcium hydroxide (Ca(OH)2) and the calcium analogue of brucite (Mg(OH)2). Occurrence Portlandite occurs in a variety ...

in 1933Web Mineral, General Portlandite Information
/ref> * Hydrocalumite in 1934 * Rankinite in 1942 * Bredigite in 1948 In all, 28 minerals have been found at this site.Habitas, Scawt Hill, Summary
/ref>

Volcanic plugs in Northern Ireland

Over 30 volcanic plugs are dotted through Northern Ireland, mostly along the Antrim coast like Scawt Hill, although they are relatively rare throughout the rest of Ireland. Volcanic plugs are often easy to spot. Their harder rock erodes away more slowly than their surroundings so they rise above the landscape as a hill. The largest volcanic plug in Northern Ireland is the oval-shaped

Slemish Slemish, historically called Slieve Mish (), is a hill in County Antrim, Northern Ireland. It lies a few miles east of Ballymena, in the townland of Carnstroan. Tradition holds that Saint Patrick, enslaved as a youth, was brought to this area a ...

. At its widest, Slemish is over 1 km in diameter. Scawt Hill is more of a typically sized example. This

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...

dolerite Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...

plug is 270 m x 180 m wide and rises 30 – 60 m above the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

white limestone (chalk), although the Antrim plateau around it is typically

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

Due to the volcanic intrusion the chalk around Scawt Hill has been transformed by high temperature and low pressure thermal metamorphism, developing the large and unusual range of calc-siliate minerals that have attracted interest. The rocks inside the vent were also changed by the contact, producing a sequence of alkali

mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks incl ...

igneous Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...

rocks as the

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

assimilated the chalk, reducing the

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...

in the magma and leading to larger grain size near the contact.

Early description of Scawt Hill

Cecil Edgar Tilley Cecil Edgar Tilley Fellow of the Royal Society, FRS HonFRSE Geological Society, PGS (14 May 1894 – 24 January 1973) was an Australian-UK, British petrologist and geologist. Life He was born in Unley, Adelaide, the youngest child of John Thoma ...

, writing for the

Mineralogical Magazine The Mineralogical Society of Great Britain and Ireland began in 1876. Its main purpose is to disseminate scientific knowledge of the Mineral Sciences (mineralogy) as it may be applied to the fields of crystallography, geochemistry, petrology, e ...

in 1929, was the first to appreciate the potential of the dolerite-limestone contact at Scawt Hill. Tilley named scawtite and larnite, and later, rankinite, and his writings inspired many others to find similar relationships between rocks worldwide.

Protected status

In 1995, Scawt Hill was categorised as an Area of Special Scientific Interest, not just for its international importance to geology, but for its plant life, where chalky and alkaline conditions are in close proximity, and for its conditions for breeding birds.Scawt Hill, ASSI, Protected Areas, Department of the Environment NI
/ref>

Ulster Way

Scawt Hill is on the

Ulster Way The Ulster Way is a series of walking routes which encircles Northern Ireland. It was founded in the 1970s by Wilfrid Merydith Capper, who was inspired by Tom Stephenson's Pennine Way. The route was relaunched in 2009 by the Department of the ...

, part of a series of walking routes which encircle Ulster. It is passed by between the Black Hill and the Sallagh Braes.Walk NI, The Ulster Way
/ref>

RAF plane crash

17 September 1943 a

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

Vickers Wellington The Vickers Wellington was a British twin-engined, long-range medium bomber. It was designed during the mid-1930s at Brooklands in Weybridge, Surrey. Led by Vickers-Armstrongs' chief designer Rex Pierson; a key feature of the aircraft is its ...

(W5647) had departed from

RAF Limavady Royal Air Force Limavady or more simply RAF Limavady is a former Royal Air Force station, also known as Aghanloo airfield, near the city of Derry, Northern Ireland. History The station was built in 1940 during the Second World War. The airfiel ...

on a training flight over the

Irish Sea The Irish Sea or , gv, Y Keayn Yernagh, sco, Erse Sie, gd, Muir Èireann , Ulster-Scots: ''Airish Sea'', cy, Môr Iwerddon . is an extensive body of water that separates the islands of Ireland and Great Britain. It is linked to the Ce ...

. The weather at RAF Limavady was getting worse and the crew was ordered to return to base. While flying low the aircraft crashed into the side of Scawt Hill, killing one of the six crew.

References

{{Geology of Northern Ireland Mountains and hills of County Antrim Volcanic plugs of Northern Ireland Paleogene volcanism Paleogene Ireland Protected areas of County Antrim Aviation accidents and incidents locations in Northern Ireland